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Cummins 6C8.3 Engine

The Cummins 6C8.3 is a heavy-duty, 8.3-liter, six-cylinder inline diesel engine widely recognized for its high power-to-weight ratio and durable performance in industrial, marine, construction, and power generation markets. Built with a unitized, structurally reinforced cast-iron cylinder block, it minimizes joint counts and flexing under heavy loads. The engine incorporates heavy-duty features including mid-stop cylinder liners to counteract cavitation, plateau-honed liner geometry for minimized oil consumption, and Ni-Resist insert pistons for long-term operational resilience. It relies entirely on a rugged mechanical architecture, making it highly serviceable and resistant to electrical system vulnerabilities. The engine architecture uses a cylinder bore of 114 mm (4.49 inches) and a piston stroke of 135 mm (5.32 inches). This configuration results in a total displacement of 8.3 liters (504.5 cubic inches), with the long-stroke geometry maximizing torque efficiency at low-to-mid range RPM.

The engine utilizes a robust fully mechanical fuel injection system for maximum field serviceability and rugged environmental compliance. Pressurized fuel processing is handled via a Bosch or Weifu mechanical inline injection pump coupled with an integrated mechanical governor for steady-state or variable speed regulation. High-pressure lines feed fuel to multi-hole, direct-injection nozzles targeting the combustion bowl directly. The primary circuit relies on a low-pressure lift pump to pull fuel through a dedicated dual-stage spin-on water separator and fine fuel filter array before entering the high-pressure gallery.

The lubrication circuit features a high-volume, gear-driven oil pump that provides a continuous flow of engine oil to high-stress friction surfaces. Standard overall system capacity (including the combination full-flow/bypass spin-on oil filters and the integrated liquid-to-liquid oil cooler) ranges between 18 and 22 liters depending on the oil pan profile specified for the equipment application. Under standard operating parameters, normal oil pressure is maintained within a range of 100 to 450 kPa (15 to 65 psi).

Engine temperature regulation is achieved through a high-capacity, jacket-water liquid-cooling system. The cylinder block and head contain between 25 and 30 liters of coolant, including the volume held in external radiators, heat exchangers, or expansion tanks. A heavy-duty mechanical thermostat restricts flow during startup, fully opening as temperatures approach normal operating ranges, with a maximum allowable engine outlet temperature limit set strictly at 95C (205F) to eliminate the risk of thermal component warping.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6C8.3
Engine Type ............... 4-cycle inline 6-cylinder direct injection liquid-cooled diesel
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.49 (114.0)
Engine Stroke, in (mm) ............... 5.31 (135.0)
Displacement, cu.in (L) ............... 505 (8.3)
Rated Engine Power, hp (kW) ............... 150-185 (110-137)
Rated Engine Speed, rpm ............... 1800-2200
Peak Torque ............... 730-915 Nm (540-675 lb-ft) at 1300-1500 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 16.5:1-17.5:1
Firing Order ............... 1-5-3-6-2-4
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure
Oil Pump Type ............... Gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 50-120

Fuel System

Fuel System ............... Direct injection
Injection Pump Type ............... Rotary or inline
Fuel System Control ............... Mechanical
Governor Type ............... Mechanical
Fuel Injector Type ............... Multi-hole
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 47.2-55.1 (1200-1400)
Overall Width, in (mm) ............... 29.5-35.4 (750-900)
Overall Height, in (mm) ............... 43.3-51.2 (1100-1300)
Dry Weight, lbs (kg) ............... 1320-1650 (600-750)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-100 kPa (10-15 psi)
Operating oil pressure ............... 300-450 kPa (44-65 psi)
Idle oil pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.012 (0.305)
Exhaust Valve Clearance, in (mm) ............... 0.024 (0.610)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CF or higher
Engine Oil Capacity, qts (L) .................. 19.9-23.1 (18.0-22.0)
Coolant Capacity, qts (L) ............... 26.3-31.5 (25.0-30.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 300 hours
Inspect air filter ............... Every 100 hours
Replace air filter ............... Every 300 hours
Change coolant ............... Every 2000 hours
Valve-lash adjustment ............... Every 1000 hours
Injector inspection ............... Every 1500-2000 hours
Compression test ............... Every 2500 hours
Drain water separator ............... As required
Belt inspection ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 4.4882-4.4894 (114.000-114.030)
Crankshaft Journal Outside Diameter, in (mm) ............... 3.8568-3.8588 (97.962-98.013)
Crank Pin Outside Diameter, in (mm) ............... 2.9906-2.9926 (75.962-76.013)
Crankshaft End Play, in (mm) ............... 0.0051-0.0150 (0.130-0.380)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3721-0.3732 (9.451-9.479)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3713-0.3724 (9.431-9.459)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.3745-0.3760 (9.512-9.550)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.3745-0.3760 (9.512-9.550)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0013-0.0039 (0.033-0.099)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0021-0.0047 (0.053-0.119)
Intake Valve Spring Free Length, in (mm) ............... 2.366 (60.10)
Exhaust Valve Spring Free Length, in (mm) ............... 2.366 (60.10)
Intake Cam Height, in (mm) ............... 1.881-1.906 (47.78-48.42)
Exhaust Cam Height, in (mm) ............... 1.898-1.924 (48.22-48.86)
Piston Pin Outside Diameter, in (mm) ............... 1.7714-1.7719 (44.993-45.005)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0002-0.0008 (0.005-0.021)
Second Ring Side Clearance, in (mm) ............... 0.0016-0.0033 (0.040-0.085)
Oil Ring Side Clearance, in (mm) ............... 0.0012-0.0030 (0.030-0.075)
Top Ring End Gap, in (mm) ............... 0.0118-0.0217 (0.30-0.55)
Second Ring End Gap, in (mm) ............... 0.0157-0.0256 (0.40-0.65)
Oil Ring End Gap, in (mm) ............... 0.0098-0.0217 (0.25-0.55)

Tightening Torque Specs

Cylinder-head bolts ............... 190-210 Nm (140-155 lb-ft)
Main-bearing caps ............... 245-260 Nm (181-192 lb-ft)
Connecting-rod bolts ............... 75-85 Nm (55-63 lb-ft)
Flywheel bolts ............... 135-150 Nm (100-111 lb-ft)
Crankshaft damper bolt ............... 270-300 Nm (199-221 lb-ft)
Oil drain plug ............... 40-50 Nm (30-37 lb-ft)
Fuel line nuts ............... 25-30 Nm (18-22 lb-ft)
Water pump bolts ............... 25-30 Nm (18-22 lb-ft)
Timing gear cover bolts ............... 20-25 Nm (15-18 ft-lb)
Injector hold-down ............... 25-30 Nm (18-22 lb-ft)

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• Cummins Engines Specs
  
• Cummins 6CT8.3 Specs
  
• Cummins 6CTA8.3 Specs
  
• Cummins 6CTAA8.3 Specs
  

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